There are many types of apparatus used in the formation of a necked end on a can body. One such type of apparatus is disclosed in U.S. Pat. No. 3,687,098 issued to J. H. Maytag, which patent is incorporated herein by reference thereto. In this patent a plurality of spaced apart circumferentially extending necking dies are fixedly mounted on a rotatable mandrel for rotation therewith. A reciprocable knock out means comprising a punch and a ram are mounted in each of the necking dies and are reciprocated by a conventional cam and cam followers. Each knock out punch has a conduit extending through it at least a portion of the knock out means have a conduit extending therethrough and one end of the conduit is connected to connecting means which connecting means extends between the one end of the conduit and a manifold having air under pressure contained therein. During the necking operation, pressurized air flows from the manifold through the connecting means and the conduit into the interior of the can body being necked to retain the integrity of the can body. In the apparatus of the '089 patent, and other similar apparatus, the necking operation is completed during a revolution of about 180 degrees by the mandrel. Therefore, the connecting means are only connected to the manifold during the 180 degrees. After this amount of rotation, the pressurized air in the connecting means and the conduit is released to atmosphere. Since most necking machines neck can bodies at the rate of 240 can bodies per minute, this is a tremendous amount of wasted pressurized air. Therefore, there exists a need to avoid this wasted pressurized air.